Tire having a carcass ply turn-up portion with a concave segment

ABSTRACT

A tire having a section height, a maximum section width, an upper section above the maximum section width, and a lower section below the maximum section width is provided. The tire includes a circumferential tread, a pair of sidewalls, a pair of bead regions each having a bead core, and at least one carcass ply extending circumferentially about the tire from one bead region to the other. The at least one carcass ply is wound outwardly about at least one of the bead cores and extends toward the tread to form a turn-up portion that terminates at a turn-up end. The turn-up portion includes a concave segment that begins in the bead region and ends short of the turn-up end or at the turn-up end.

FIELD OF THE INVENTION

The present application relates to tires and, more particularly, to atire having a carcass ply turn-up portion with a concave segment toimprove lower sidewall performance of the tire.

BACKGROUND

In an inflated and loaded condition, a radial tire is subject to bendingmoments at the lower sidewall areas at the center of the tire footprint.The strains and stresses created by the moments are directly related tothe lower sidewall performance of the tire.

Previous research and studies have demonstrated that increasing lowersidewall stiffness can reduce tire deformation in the region and improvelower sidewall performance. Because of the interaction between the wheelflange and tire contour in its mounting region, the lower sidewall of arolling tire experiences high stress and strain cycles. Many engineeringtechniques and design methods have been developed to reduce stress andstrain in the region.

SUMMARY

In one embodiment, a tire having a section height, a maximum sectionwidth, an upper section above the maximum section width, and a lowersection below the maximum section width is provided. The tire includes acircumferential tread, a pair of sidewalls, a pair of bead regions eachhaving a bead core, and at least one carcass ply extendingcircumferentially about the tire from one bead portion to the other. Theat least one carcass ply is wound outwardly about at least one of thebead cores and extends toward the tread to form a turn-up portion thatterminates at a turn-up end. In this embodiment, the turn-up portion hasa height that is less than about 50% of the section height of the tireand includes a concave segment that extends from the bead region to theturn-up end.

In another embodiment, a tire having a section height is provided. Thetire includes a circumferential tread, a pair of sidewalls, a pair ofbead portions each having a bead core, and at least one carcass plyextending circumferentially about the tire from one bead portion to theother. The at least one carcass ply is wound outwardly about at leastone of the bead cores and extends toward the tread to form a turn-upportion that terminates at a turn-up end. In this embodiment, a sectionof the turn-up portion follows a concave path that begins at a height ofabout 10 mm to about 20 mm and terminates at a height that is betweenabout 20% to about 50% of the section height of the tire, wherein theheights are measured from the base of the bead core.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, together with the detailed descriptionprovided below, describe exemplary embodiments of the claimed invention.In the drawings and description that follow, like elements areidentified with the same reference numerals. The drawings are not toscale and the proportion of certain elements may be exaggerated for thepurpose of illustration.

FIG. 1 is a cross-sectional view of one embodiment of half of a tire100.

FIG. 2 is an enlarged perspective view of a portion of the tire 100 ofFIG. 1.

FIG. 3 is a cross-sectional view of another embodiment of half of a tire300.

FIG. 4 is a cross-sectional view of another embodiment of half of a tire400.

DETAILED DESCRIPTION

The following includes definitions of selected terms employed herein.The definitions include various examples and/or forms of components thatfall within the scope of a term. The examples are not intended to belimiting.

“Axial” or “axially” refer to a direction that is parallel to the axisof rotation of a tire.

“Circumferential” and “circumferentially” refer to a direction extendingalong the perimeter of the surface of the tread parallel to theequatorial plane perpendicular to the axial direction of the tire.

“Equatorial plane” refers to the plane that is perpendicular to thetire's axis of rotation and passes through the center of the tire'stread.

“Groove” refers to an elongated void in the tread of the tire thatextends circumferentially in a straight, curved or zig-zag manner.

“Lateral” or “laterally” refer to a direction along the tread of thetire going from one sidewall of the tire to the other sidewall.

“Radial” or “radially” refer to a direction perpendicular to the axis ofrotation of the tire.

“Sidewall” refers to that portion of the tire between the tread and thebead.

“Tread” refers to that portion of the tire that comes into contact witha surface under normal load.

Directions are also stated in this application with reference to theaxis of rotation of the tire. The terms “upward” and “upwardly” refer toa general direction towards the tread of the tire, whereas “downward”and “downwardly” refer to the general direction towards the axis ofrotation of the tire. Thus, when relative directional terms such as“upper” and “lower” are used in connection with an element, the “upper”element is spaced closer to the tread than the “lower” element.Additionally, when relative directional terms such as “above” or “below”are used in connection with an element, an element that is “above”another element is closer to the tread than the other element. The terms“inward” and “inwardly” refer to a general direction towards theequatorial plane of the tire, whereas “outward” and “outwardly” refer toa general direction away from the equatorial plane of the tire andtowards the sidewall of the tire. Thus, when relative directional termssuch as “inner” and “outer” are used in connection with an element, the“inner” element is spaced closer to the equatorial plane of the tirethan the “outer” element.

Illustrated in FIG. 1 is a cross-sectional view of half of oneembodiment of a tire 100. Although only half of the tire 100 is depictedin the drawings, it will be appreciated that the other half of the tire100 is a substantial mirror image of the half depicted. The tire 100 hasan equatorial plane E_(p) and one half of a maximum section width W_(m)measured from the equatorial plane E_(p) to the outer most point of thetire 100 (i.e., point X). The tire 100 can be divided into twosections—an upper section U and a lower section L. Separating the uppersection U from the lower section L is a hypothetical line Y drawnthrough point X that is parallel to the axis of rotation of the tire100. The upper section U is the portion of the tire 100 that is disposedabove the hypothetical line Y with the maximum section width W_(m) ofthe tire 100, while the lower section L is disposed below thehypothetical line Y with the maximum section width W_(m) of the tire100.

With continued reference to FIG. 1, the tire 100 includes a tread 102provided in the upper section U of the tire 100, a sidewall 104 providedin both the upper and lower sections U, L of the tire 100, and a beadportion or region 106 provided in the lower section L of the tire 100.The bead portion 106 includes a bead core 108 and a bead filler 110having an upper end 112.

The tire 100 further includes first and second carcass plies 114, 116that extend circumferentially about the tire 100 from one bead region(e.g., bead region 106) to the other bead region (not shown). The firstand second carcass plies 114, 116 are wound outwardly about the beadcore 108 and extend upwardly towards the tread 102 to form first andsecond turn-up portions 118, 120, respectively, which will be discussedin further detail below. Each turn-up portion 118, 120 terminates at aturn-up end 122, 124, respectively. Although the tire 100 illustrated inFIG. 1 includes two carcass plies, the tire 100 can include a singlecarcass ply or more than two carcass plies in alternative embodiments(not shown).

In one embodiment, the first and second carcass plies 114, 116 includeparallel-aligned cords that are radially disposed. In other words, theparallel-aligned cords are oriented substantially perpendicular to theequatorial plane E_(p) of the tire 100. In alternative embodiments, oneor more of the carcass plies can include parallel-aligned cords that arebiased with respect to the equatorial plane E_(p) of the tire 100. Inall cases, the cords can be constructed of, for example, nylon orpolyester or rayon.

With continued reference to FIG. 1, the tire 100 further includes firstand second belts 126, 128 that extend circumferentially about the tire100. The first and second belts 126, 128 are provided between the tread102 and the first and second carcass plies 114, 116 as shown in FIG. 1.The first and second belts 126, 128 terminate at edges 130, 132,respectively, at a location near a shoulder region 134 of the tire 100.Although the tire 100 illustrated in FIG. 1 features two belts, the tire100 can include a single belt or more than two belts in alternativeembodiments (not shown).

In one embodiment, the first and second belts 126, 128 includeparallel-aligned cords or wires that are radially disposed. Inalternative embodiments, one or more of the belts can includeparallel-aligned cords or wires that are biased with respect to theequatorial plane E_(p) of the tire 100. In all cases, the cords or wirescan be constructed of, for example, steel or other steel alloys.

With continued reference to FIG. 1, the tire 100 also includes a beltedge insert 136 provided in the shoulder region 134 of the tire 100between the edges 130, 132 of the first and second belts 126, 128,respectively, and the first and second carcass plies 114, 116. The beltedge insert 136 has an inner end 138 and an outer end 140. The belt edgeinsert 136 is configured to protect the carcass plies 114, 116 from theedges of the belts 126, 128. The belt edge insert 136 may be constructedof extruded rubber or another elastomeric material. Although shown inthe FIG. 1 embodiment, the belt edge insert 136 is optional and may beomitted in alternative embodiments (not shown).

The tire 100 further includes a tread cap 142 provided between the tread102 and the first and second belts 126, 128. The tread cap 142 can beused to assist in holding the components of the tire together (e.g., thebelts, plies, and tread). The tread cap 142 can include, for example,one or more polyester or nylon fabric plies. Although shown in the FIG.1 embodiment, the tread cap 142 is optional and may be omitted inalternative embodiments (not shown).

With continued reference to the embodiment illustrated in FIG. 1, thefirst turn-up portion 118 of the first carcass ply 114 has a height Himeasured radially from the turn-up end 122 to the base of the bead core108, while the second turn-up portion 120 of the second carcass ply 116has a height H₂ measured radially from the turn-up end 124 to the baseof the bead core 108. In the illustrated embodiment, H₁ is greater thanH₂.

In one embodiment, the height H₁ of the first turn-up portion 118 isless than about 50% of the section height H₀ of the tire 100 (which ismeasured from the outer tread surface at the equatorial plane E_(p) tothe base of the bead core 108). In another embodiment, the height H₁ ofthe first turn-up portion 118 is between about 25% and about 50% of thesection height H₀ of the tire 100. Preferably, the height H₁ of thefirst turn-up portion 118 is between about 40% and about 50% of thesection height H₀ of the tire 100.

In one embodiment, the height H₂ of the second turn-up portion 120 canbe less than about 35% of the section height H₀ of the tire 100.Preferably, the height H₂ of the second turn-up portion 120 is betweenabout 10% and about 35% of the section height H₀ of the tire 100.

In the illustrated embodiment, the first turn-up portion 118 of thesecond carcass ply 114 includes a concave section or segment 144 thatfollows a concave path (hereinafter referred to as “concave segment144”). For illustration purposes, the concave segment 144 of the turn-upportion 118 is hatched in order to differentiate it from the rest of theturn-up portion 118.

Illustrated in FIG. 2 is an enlarged view of a portion of the tire 100of FIG. 1 depicting the shape and orientation of the concave segment 144of the first turn-up portion 118 in greater detail. As shown in FIG. 2,the concave segment 144 of the first turn-up portion 118 begins in thebead region 106 and terminates short of the first turn-up end 122 of theturn-up portion 118. Although the concave segment 144 of the firstturn-up portion 118 in the illustrated embodiment terminates short ofthe second turn-up end 122 of the first turn-up portion 118, the firstturn-up end 122 can terminate at the second turn-up end 122 of the firstturn-up portion 118 in another embodiment (not shown).

The beginning and end of the concave segment 144 can also be discussedin terms of height relative to the base of the bead core 108. In oneembodiment, the concave segment 144 of the first turn-up portion 118 canbegin in the bead region 106 (e.g., at a height H₃ of about 10 mm toabout 20 mm, preferably 15 mm) and terminate at a height (e.g., H₄) ofbetween about 20% and about 50% of the section height H₀ of the tire100. In another embodiment, the concave segment 144 can terminate at aheight H₄ of between about 20% and 35% of the section height H₀ of thetire 100.

As shown in FIG. 2, the concave segment 144 of the first turn-up portion118 follows a continuous concave path that is a portion of a circle(e.g., an arc) that is defined by a single radius R. In one embodiment,the radius R of the concave segment 144 is between about 380 mm andabout 1500 mm. Preferably, the radius R of the concave segment 144 isbetween about 800 mm and about 1000 mm. In alternative embodiments (notshown), the concave segment 144 of the first turn-up portion 118 mayfollow a concave path that is defined by two or more radii with tangents(viewed in cross section) that work together to form a continuoussurface. Moreover, in other embodiments (not shown), the concave segment144 may be parabolic-shaped or may be defined by an irregular concaveshape.

To force the concave segment 144 to follow the continuous concave path,the tire 100 can be constructed in at least three configurations.

In one configuration, the tire can include an insert that is structuredand arranged to assist, at least in part, in forming the concave segment144 of the first turn-up portion 118. Illustrated in FIG. 3 is across-sectional view of another embodiment of half of a tire 300depicting one embodiment of an insert 302 provided therein. The tire 300is similar to and includes the same components as the tire 100, exceptthat the tire 300 includes the insert 302. Although FIG. 3 illustratesonly half of a cross-section of the tire 300, a second insert, similarto the insert 302 described above and illustrated in FIG. 3, can beprovided in the other sidewall (not shown) of the tire 300.

With reference to FIG. 3, the insert 302 extends circumferentially aboutthe tire 300, and includes an upper end 304 that terminates in the uppersection U of the tire 300 and a lower end 306 that terminates in thelower section L of the tire 300. In another embodiment (not shown), theupper end 304 of the insert 302 can terminate in the lower section L ofthe tire 300.

In the illustrated embodiment, the insert 302 is positioned between thefirst turn-up portion 118 of the first carcass ply 114 and the sidewall104 of the tire 300. In an embodiment where the tire 300 includes onlyone carcass ply (not shown), the insert 302 is provided between suchcarcass ply and the sidewall 104 of the tire 300.

As shown in FIG. 3, the lower end 306 of the insert 302 extends belowthe second turn-up end 124 of the second turn-up portion 120. In otherwords, the insert 302 overlaps the second turn-up portion 120.Preferably, the lower end 306 of the insert 302 extends below the secondturn-up end 124 of the second turn-up portion 120 a radial distance D₁between about 6 mm and about 12 mm.

Similarly, the upper end 304 of the insert 302 extends above the firstturn-up end 122 of the first turn-up portion 118. Preferably, the upperend 304 of the insert 302 extends above the first turn-up end 122 of thefirst turn-up portion 118 a radial distance D₂ between about 6 mm andabout 24 mm.

The insert 302 can be constructed from a variety of materials including,without limitation, an elastomeric material (e.g., rubber). In oneembodiment, the insert 302 is constructed from an elastomeric materialhaving a higher modulus of elasticity than the material from which thesidewall 104 is constructed.

The insert 302 described above and illustrated in FIG. 3 is configuredto force the concave segment 144 to follow the continuous concave pathdiscussed above. Due to its cross-sectional shape, construction, andposition within the tire 300, the insert 302 is capable of forcing thefirst turn-up portion 118 inward, thereby defining, at least in part,the concave segment 144.

In a second configuration (not shown), the insert 302 described aboveand illustrated in FIG. 3 can be an extension of one or both sidewallsof the tire, instead of being a separate component. For example, thecross-sectional shape of the extruded rubber strips that form thesidewalls of the tire can be modified to take into account the extramaterial needed to cause the concave segment 144 to follow the concavepath discussed above in a similar manner described above. In otherwords, each extruded strip can include a portion that replaces theinsert 302 described above and illustrated in FIG. 3 (hereinafterreferred to as “insert portion”) in addition to the remaining portionthat makes up the sidewall of the tire. In this configuration, theextruded rubber strips that form the sidewalls of the tire will beconstructed of the same elastomeric material. However, in an alternativeembodiment, the rubber strips that form the sidewalls of the tire may beconstructed of two or more different materials made in a co-extrusionprocess. In this alternative embodiment, the insert portion of eachrubber strip can be made of an elastomeric material having a highermodulus of elasticity than the remaining portion that makes up thesidewall of the tire.

In a third configuration, the tire can include a reinforcement ply thatis structured and arranged to assist, at least in part, in forming theconcave segment 144 of the first turn-up portion 118. Illustrated inFIG. 4 is a cross-sectional view of another embodiment of half of a tire400 depicting one embodiment of an reinforcement ply 402 providedtherein. The tire 400 is similar to and includes the same components asthe tire 100, except that the tire 400 includes the reinforcement ply402. Although the tire 400 features a single reinforcement ply 402, twoor more reinforcement plies can be employed in alternative embodiments(not shown). Moreover, although FIG. 4 illustrates only half of across-section of the tire 400, a second reinforcement ply, similar tothe reinforcement ply 402 described above and illustrated in FIG. 4, canbe provided in the other sidewall (not shown) of the tire 400.

The reinforcement ply 402 extends circumferentially about the tire 400and is provided between the first turn-up portion 118 and the sidewall104 of the tire 400. In an embodiment where the tire 400 includes onlyone carcass ply (not shown), the reinforcement ply 402 is providedbetween the single carcass ply and the sidewall 104 of the tire 400.

As shown in FIG. 4, the reinforcement ply 402 includes an upper edge 404that terminates in the upper section U of the tire 400 and a lower edge406 that terminates in a lower section L of the tire 400. In anotherembodiment (not shown), the upper edge 404 of the reinforcement ply 402can terminate in the lower section L of the tire 400.

With reference to FIG. 4, the upper edge 404 of the reinforcement ply402 extends beyond the first turn-up end 122 of the first turn-upportion 118. Preferably, the upper edge 404 of the reinforcement ply 402extends beyond the first turn-up end 122 of the first turn-up portion118 a radial distance D₃ between about 6 mm and about 24 mm.

In the illustrated embodiment, the lower edge 406 of the reinforcementply 402 is folded up towards the tread 102 of the tire 400, therebyforming a fold-up portion 408 and a crease 410. The fold-up portion 408cooperates with the adjacent portion of the reinforcement ply 402 fromwhich it overlaps to form a dual layer reinforcement. Preferably, theradial distance D₄ between the crease 410 and the end of the fold-upportion 408 of the reinforcement ply 402 (i.e., the lower edge 406) isbetween about 6 mm and about 24 mm. The extent of the fold can also bediscussed in relation to fold percentage (i.e., the relationship betweenthe length of the fold-up portion 408 of the reinforcement ply 402 andthe length of the remaining portion of the reinforcement ply 402 definedbetween the crease 410 and the upper edge 404 of the reinforcement ply402). Preferably, the fold-up portion 408 can have a fold percentagebetween about 25% and about 50%. In another embodiment (not shown), thefolded reinforcement ply 402 can be replaced with two or more separatepieces of ply material cut to different lengths.

With continued reference to FIG. 4, the crease 410 of the reinforcementply 402 extends below the second turn-up end 124 of the second turn-upportion 120. Preferably, the crease 410 of the reinforcement ply 402extends below the second turn-up end 124 of the second turn-up portion120 a radial distance D₅ between about 6 mm and about 12 mm.

Additionally, the lower edge 406 of the reinforcement ply 402 extendsabove the second turn-up end 124 of the second turn-up portion 120.Preferably, the lower edge 406 of the reinforcement ply 402 extendsbeyond the second turn-up end 124 of the second turn-up portion 120 aradial distance D₆ between about 6 mm and about 12 mm.

The reinforcement ply 402 is constructed of a set of parallel-alignedcords encapsulated in rubber or another elastomeric material. In oneembodiment, the set of parallel-aligned cords are radially disposed. Inother words, the parallel-aligned cords are oriented substantiallyperpendicular to the equatorial plane E_(p) of the tire 400. Inalternative embodiments, the reinforcement ply 402 can includeparallel-aligned cords that are biased with respect to the equatorialplane E_(p) of the tire 400. In all cases, the cords can be constructedof, for example, nylon or polyester.

In one embodiment, the reinforcement ply 402 has a thickness betweenabout 0.5 mm and about 1.0 mm. Preferably, the reinforcement ply 402 hasa thickness of about 0.9 mm.

The reinforcement ply 402 described above and illustrated in FIG. 4 isconfigured to force the concave segment 144 to follow the continuousconcave path discussed above. Due to its construction and positionwithin the tire 400, the reinforcement ply 402 (specifically the fold-upportion 408 and the adjacent portion of the reinforcement ply 402 fromwhich it overlaps) is capable of forcing the first turn-up portion 118inward, thereby defining, at least in part, the concave segment 144.

By providing a tire that includes a carcass ply turn-up portion having aconcave segment similar to the one discussed above, sidewall performanceof the tire can be improved. Specifically, the existence of the concavesegment in the carcass ply turn-up portion can reduce lower sidewallstrain energy density. Reduction of strain energy density in the lowersidewall region of the tire can lead to an improvement in durability(e.g., a reduction of possible separation between the sidewall and thebodyply of the tire), a reduction of deflection of the sidewall, and/oran improvement in vehicle handling.

To the extent that the term “includes” or “including” is used in thespecification or the claims, it is intended to be inclusive in a mannersimilar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “or” is employed (e.g., A or B) it is intended to mean “Aor B or both.” When the applicants intend to indicate “only A or B butnot both” then the term “only A or B but not both” is employed. Thus,use of the term “or” herein is the inclusive, and not the exclusive use.See, Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed.1995). Also, to the extent that the terms “in” or “into” are used in thespecification or the claims, it is intended to additionally mean “on” or“onto.”

While the present application illustrates various embodiments, and whilethese embodiments have been described in some detail, it is not theintention of the applicant to restrict or in any way limit the scope ofthe claimed invention to such detail. Departures may be made from suchdetails without departing from the spirit or scope of the applicant'sclaimed invention. Therefore, the invention, in its broader aspects, isnot limited to the specific details, the representative apparatus, andillustrative examples shown and described.

1. A tire having a section height, a maximum section width, an uppersection above the maximum section width, and a lower section below themaximum section width, the tire comprising: a circumferential tread; apair of sidewalls; a pair of bead regions, each having a bead core; atleast one carcass ply extending circumferentially about the tire fromone bead region to the other, wherein the at least one carcass ply iswound outwardly about at least one of the bead cores and extends towardthe tread to form a turn-up portion that terminates at a turn-up end,wherein the turn-up portion has a height that is less than about 50% ofthe section height of the tire, wherein the turn-up portion includes aconcave segment that extends from the bead region to the turn-up end;and at least one reinforcement ply extending circumferentially about thetire and provided between the turn-up portion and one of the sidewalls,wherein a lower edge of the at least one reinforcement ply terminates inthe lower section of the tire and an upper edge of the at least onereinforcement ply terminates in the upper section of the tire; whereinthe at least one reinforcement ply includes a fold-up portion and acrease.
 2. The tire of claim 1, wherein the turn-up portion has a heightthat is between about 25% and about 50% of the section height of thetire.
 3. The tire of claim 1, wherein the concave segment of the turn-upportion has a radius between about 380 mm to about 1500 mm.
 4. The tireof claim 1, further comprising a second carcass ply wound outwardlyabout the bead core and extends toward the tread to form a secondturn-up portion that terminates at a second turn-up end, wherein thesecond turn-up portion has a height that is less than about 35% of thesection height of the tire.
 5. The tire of claim 1, wherein the creaseof the at least one reinforcement ply extends below the turn-up portion.6. The tire of claim 1, wherein the at least one reinforcement plyincludes cords constructed of nylon.
 7. The tire of claim 1, wherein alower edge of the reinforcement ply is folded up towards the tread ofthe tire at a fold percentage of between about 25% and 50%.
 8. The tireof claim 1, wherein the reinforcement ply includes cords constructed ofnylon.